The riot came just hours after an overnight battle in southern Afghanistan that a provincial governor said killed at least 50 suspected Taliban rebels and two Afghan soldiers.

More than 800 people have died in a surge of insurgent attacks and government offensives since March, and U.S. and Afghan officials have warned that the violence is a threat to parliamentary elections scheduled for Sept. 18.

Police in eastern Paktika province said a legislative candidate was killed Tuesday by a roadside bomb that blew up next to his vehicle as he drove his sick mother to the hospital. The woman was wounded, area police chief Malik Khan said.

The clash in Bagram was unusual. The area an hour's drive north of the capital has been largely peaceful since a U.S.-led military campaign toppled the Taliban regime in late 2001 for harboring Osama bin Laden and al-Qaida terrorist camps.

Rioting broke out in a crowd of more than 1,000 people who gathered to protest the detention of eight villagers at the base, where thousands of U.S. and other foreign soldiers live behind razor-wire fences and land mines left from Afghanistan's civil war.

Demonstrators hurled stones at a passing convoy of six U.S. military vehicles, smashing some windows. As soldiers inside the cars fired handguns in the air, the vehicles sped into the base and the protesters chased behind, trying to push down a metal gate guarded by Afghan troops.

Guards used sticks to drive back the mob as other troops fired into the air with assault rifles and shouted at the protesters to go home. Most of the protesters then dispersed.

It was not clear if there were any casualties, though an Associated Press reporter was hit and kicked by protesters who accused him of being a spy for the Americans and an AP photographer was punched by other demonstrators.

The eight detained men were "suspected of planning and conducting attacks against U.S. and Afghan forces" and had "materials used to make improvised explosive devices in their possession," the U.S. military said in a statement.

The demonstrators said they were angry that U.S. troops arrested the villagers late Monday without consulting local authorities.

"We have supported the Americans for years. We should be treated with dignity," said Shah Aghar, 35. "They are arresting our people without the permission of the government. They are breaking into our houses and offending the people. We are very angry."

In the south, Uruzgan Gov. Jan Mohammed Khan said Afghan and U.S. troops inflicted heavy casualties in attacking a guerrilla base in the Dihrawud district. He said two Afghans and at least 50 rebels were killed and about 25 suspected insurgents were captured.

Attempts to confirm the casualty toll with other Afghan officials and the U.S. military were not successful.

A U.S. military statement Monday said heavy fighting in that area had killed one American soldier, an Afghan trooper and 11 rebels. Three Americans and one Afghan soldier were wounded, it said.

The statement said U.S. jets and helicopters joined a battle that began with a rebel attack on a patrol.

In other incidents:

--Police arrested 10 suspected Taliban insurgents after clashes in southeastern Zabul province, said Ali Khail, a spokesman for the provincial governor.

--Guerrillas attacked an Afghan patrol in Kandahar province late Monday, triggering a gunbattle that left an Afghan soldier dead and a police officer badly wounded, deputy district chief Haji Lala Khan said.